list=[1,2,3,2]
a=list[0]
for i in list:
    if i > a:
        a = i
print(a)

list2=[1,2,3,4,'a',1]
sum=0
for i in list2:
    if isinstance(i,int):
        sum=sum+i
print(sum)

x=6
for i in range(2,x):
    if x % i == 0:
        print("不是素数")
        break
else:
    print("是素数")

x=10
sum = 0
for i in range(2,x+1):
    for j in range(2,i):
        if i % j == 0:
            break
    else:
        sum = sum+1
print(sum)

